THE DISTRIBUTION OF TENASCIN-R IN THE DEVELOPING AVIAN NERVOUS-SYSTEM

Tenascin-R is an extracellular matrix glycoprotein found in the develo ping central nervous system. In vitro, tenascin-R promotes axon growth . In order to learn more about the function and regulation of tenascin -R in neural development, we have used monoclonal antibodies to locali ze tenascin-R immunoreactivity in the developing and adult chicken bra in. The earliest stage stained with anti-tenascin-R was embryonic day 6.5, when the matrix surrounding the cell bodies of spinal cord motone urons was stained. At embryonic day 18, specific brain regions were st ained, including the basal nuclei, habenular nuclei, layer ''i'' of th e optic tectum, and the motor nuclei of cranial nerves. Anti-tenascin- R staining persisted in these regions in the adult chicken brain. Thus , the distribution of tenascin-It immunoreactivity in the developing a nd mature avian brain is correlated with the distribution of nerve gro wth factor (NGF)-sensitive neurons, but it is not correlated with neur ite outgrowth. Finally, NGF was shown to upregulate tenascin-R express ion in PC12 cells, indicating that expression of neuron-derived tenasc in-R may be regulated by exogenous NGF. (C) 1998 Wiley-Liss, Inc.